1. Field of the Invention
The present invention relates to a method of manufacturing semiconductor device, and more particularly to a method of manufacturing different-voltage semiconductor devices.
2. Description of Related Art
The single chip process for integrating power switches with control circuitry is a major trend in the field of power IC development. Its objective is to integrate high-voltage devices and low-voltage devices in a single process for reducing the manufacturing cost and increasing industrial utilization. However, in traditional applications the process is complicated and the disturbance between high-voltage devices and low-voltage devices is unavoidable. Meanwhile, since electronic characteristics of high-voltage devices and low-voltage devices are different, e.g. threshold voltage, there exist lots of difficulties in circuit design. Traditional processes usually have their own structures or procedures particularly for high-voltage transistor, but those structures or procedures would reduce utilization and increase the manufacturing cost.
Therefore, a method for manufacturing different-voltage devices in a single process while compatible with a standard process is desired.